Sega-Galaga (セガ・ギャラガ) is the SG-1000 port of Galaga, and is strangely the only port to receive a name change.
The player pilots a starship and must destroy all the on-screen enemies, similar to Space Invaders and Galaxian. However, the enemies in Galaga have the power to steal your ship to use as reinforcements (meaning the player loses a life). However, if you are able to destroy the enemy who has captured your ship, you are able to pilot both ships at once, doubling your firepower at the expense of being a bigger target.
Though Sega-Galaga is essentially the same game as the arcade original, the limiations of the SG-1000 means the graphics and sound are not quite as advanced. Also the "challenging stages" have been omitted, meaning each stage is identical to the last.